Determination of Primary Energy and Mass in the PeV Region by Bayesian Unfolding Techniques

The field detector array of the KASCADE experiment measures the electron and muon component of extensive air showers in the knee region with high precision. A baysian unfolding procedure is presented in which the two-dimensional shower size distribution (Ne, Nμtr) is examined. On the arbitrary assumption that the chemical composition consists of five primary mass groups (hydrogen, helium, carbon, silicon and iron) the size distribution is deconvoluted to reconstruct the energy spectra of these mass groups in the energy range between 1015 eV and 1017 eV. The energy spectra of the lighter element groups result in a knee-like bending with a steepening above the knee. The topology of the individual knee positions suggest a rigidity dependence.